C# continues to gain popularity among developers, now ranking as the fifth most popular software development language. Its deep integration into the Microsoft ecosystem offers a streamlined development experience across multiple platforms. And thanks to its versatility, C# is now extending beyond traditional boundaries, making significant progress in mobile, web, and cloud computing.
As the language is transforming the development landscape, Vitalii Datsyshyn, an associate solution architect at Intellias, outlines the key questions you may encounter when applying for a position as a C# developer.
Junior Level
Taking your first steps into C# coding, you should expect that your foundational knowledge, problem-solving skills, and readiness for the role will be tested. The list of interview questions for Junior C# developers might be as follows:
- What data types are available in C#? What are the differences between them?
- What is a conditional statement and how can you use it?
- What is a for loop and how can you use it for repetitive actions?
- What is an array and how do you declare and use it in C#?
- What are the main principles of OOP and how are they implemented in C#?
- What is the difference between an abstract class and an interface in C#?
- What is the difference between structures (struct) and classes (class) in C#?
- What are exceptions and how do you handle them in C#? How can you create custom exceptions?
- What are the access modifiers in C# and what do they mean?
- What are the uses of try, catch, and finally? Under what circumstances might the finally block not execute? If an exception is caught in a catch block, what is the difference between throw vs throw ex vs throw new Exception()?
- What collections are you familiar with?
- What is the difference between a regular class and a static class?
- What is the difference between const and readonly?
- What is a namespace and how do you use it to organize code in C#?
- What are the advantages of using LINQ in C#?
- What are delegates, and how do you use them to implement callbacks in C#?
Middle Level
A mid-level C# developer role requires a deeper understanding of programming concepts and practical experience. Potential employers would be interested in your project experience and ability to contribute to complex projects. At an interview, you may be asked:
- What is the difference in method overriding between the new and override keywords?
- What is multithreading and how is it implemented in C#?
- What is the difference between String and StringBuilder in C#, and when is it better to use each?
- What is the difference between eager and lazy loading?
- How can polymorphism be implemented in C# using virtual and overridden methods?
- What design patterns do you use in C#, and can you provide examples of their use?
- How do you use attributes in C# and what are they needed for?
- What is serialization in C# and how is it used to save objects?
- How do you use asynchronous programming in C# using the async and await keywords?
- How can reflection be used in C# to dynamically obtain information about types and their members?
- How is the Singleton pattern implemented in C# and what are its advantages and disadvantages?
- What is the purpose of the using keyword? How is it related to the Disposable pattern?
- What is the LinkedList<T> collection used for? How does it differ from other collections?
- What is the difference between IList and IEnumerable?
- What is the difference between IEnumerable and IQueryable?
- Why is a ThreadPool necessary? Describe its mechanics: How is a thread allocated and returned to the ThreadPool?
- What are the methods for thread synchronization? What is a lock?
- What does immutable mean? What types are immutable?
- How does a record differ from a class?
- What is the garbage collector? What are generations? When does GC start cleaning?
Senior Level
When applying for a senior role, be ready to demonstrate your advanced technical knowledge and strategic thinking. Questions you might expect at a job interview for a senior C# developer role are as follows:
- What design patterns are implemented in C#, and can you provide examples of their use?
- How does async/await work in detail? Why should you not use async void methods?
- What is an expression tree?
- What is a race condition?
- How can you use type indexing in C# to dynamically create objects and invoke methods at runtime?
- How can you use dynamic types in C# to handle objects whose types are only known at runtime?
- How can you implement custom extension methods for existing types in C#?
- How can you manage and use memory with unsafe code and pointers in C#?
- How can you implement and utilize your own monitoring and logging mechanisms in C# to track program performance and identify issues?
While these questions focus on C#, it’s crucial to remember that actual interviews will encompass a broader range of topics. Prepare to discuss software architecture and design, Git, code quality, cloud computing, CI/CD, databases, and service communication. We will delve into more insights on these essential areas in our next articles.
Once you have reviewed these interview questions, be sure to take the next step and apply for the desired position. Check out C# vacancies for all levels and in cutting-edge industries on the Intellias website.
